Geological Survey Bulletin Volume a 1422

Geological Survey Bulletin Volume a 1422

By (author) 

List price: US$19.99

Currently unavailable

Add to wishlist

AbeBooks may have this title (opens in new window).

Try AbeBooks


This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. Excerpt: ...area. In the measured section at Cottonwood Creek (fig. 3), the Parkman is 59 m (193 ft) thick and consists of light-gray and olive-gray, fine-grained, thin-bedded, crossbedded, mottled in places, biotitic, noncalcareous and calcareous, quartzose sandstone, interbedded with greenish-gray siliceous mudstone, minor orange-weathering volcanic sandstone and conglomeratic volcanic sandstone, and one 6-m (20-ft)-thick bed of biotite-rich welded tuff. The uppermost light-gray sandstone is characterized by contorted bedding in the measured section, probably a result of contemporaneous slump deformation. Leaf and twig imprints are common in some of the mudstone beds. This unit is thought to be the rock-stratigraphic equivalent of the thin marine sandstone placed at the top of the Eagle Sandstone at Bruno Siding (figs. 1, 4) by Gill (Gill and others, 1972, p. 92), who earlier had called it Parkman Sandstone (Gill and Vaughn, in McMannis and others, 1968; and then again in Gill and Cobban, 1973, p. 16). Roberts (1972, p. C43) suggested that a thin calcareous quartzose sandstone 156 m (510 ft) above the base of the Cokedale Formation at Cokedale might be a western tongue of the Parkman Sandstone. MIDDLE SANDSTONE MEMBER The middle sandstone member comprises a thick (305-503 m (1,000-1,650 ft)) ridge-forming series of epiclastic volcanic sandstones interbedded with epiclastic volcanic conglomerate, mudflow conglomerate, and minor volcanic siltstone and mudstone (fig. 5). The member is 491 m (1,611 ft) thick in the type section of the Sedan Formation at Cottonwood Creek. The sandstones are light olive green, olive gray, and dark greenish gray; range from fine grained to conglomeratic, but are commonly medium to coarse grained; are calcareous; are mottled in places; and more

Product details

  • Paperback | 82 pages
  • 189 x 246 x 4mm | 163g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236591321
  • 9781236591326